lower back panel grille
Here's two pics showing the difference between the fastback version and the coupe/conv version. Note that the fastback grille is straight across the top, while the coupe/conv dips in the middle to account for the shape of the deck/trunk lid.
The fastback body is Nightmist blue with the optional two tone paint on the grille.
These grilles were procured with 3 busted posts out of 8 total. A local old time welder actually repaired them for $20, but that was ~1985. He did say that the repair was a labor of love, and not too many people had the skill set required to make that particular repair.
The Ford buyer's digest from 1967 lists the "lower back panel grille" at $19.48, and the "two tone paint (lower back grille)" at $12.95. If the grille was purchased without the two tone paint option, it would be body color. There was no factory silver/shiny/chrome appointments.
Ford part numbers for the coupe/conv version:
Regarding mounting, the 12 connections at the lamp housing are drilled & tapped, accepting the same studs as the standard chrome trim. The nuts with built in water resistant filler is the same as standard chrome trim. The protective plastic caps are also the same.
Turning to the 8 studs unique to the grilles, these should have square black rubber washers with one side cut at an angle to match up with the concave sheet metal panel. The nut is a cap nut so that there are no sharp studs to catch something on. I've included a picture of one of these as well.
Hope this helps.